Oral-History:John Moll

About John Moll

John Moll wanted to be an engineer or scientist from an early age, and he attended Ohio State University for his bachelor’s in physics. Graduating during World War II, Moll joined the war effort by working at RCA on magnetrons for radar jamming. Moll returned to Ohio State University for his doctorate in electrical engineering, which he received in 1952. During his long career, Moll worked at Bell Labs, Fairchild, Hewlett Packard and taught at Stanford. He took part in both device fabrication and research, building upon his interest in semiconductors, and worked with junction transistors, integrated circuits, solid-state switches, crystals, silicon, MOS and gallium arsenide. Moll is also famous for the Ebers-Moll Equations and p-n-p-n switch theory.

In this interview, Moll discusses his career and the semiconductor device industry. Talking about many of the developments since the 1950s, Moll covers the transitional time of moving away from vacuum tubes and the use of silicon over germanium. Moll also discusses the differences between device fabrication and research, and the ways in which inefficiencies can be avoided in technological development. He also talks about working at Bell and Hewlett Packard, along with various colleagues such as Jack Morton, Joe Klimack and Nick Holonyak.

About the Interview

JOHN MOLL: An Interview Conducted by Andrew Goldstein, IEEE History Center, 21 May 1993

Interview #159 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc.

Copyright Statement

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It is recommended that this oral history be cited as follows:

John Moll, an oral history conducted in 1993 by Andrew Goldstein, IEEE History Center, Hoboken, NJ, USA.

Interview

Interview: John Moll

Interviewer: Andrew Goldstein

Date: 21 May 1993

Location: Hewlett Packard, Palo Alto, California

Bell, Silicon Technology and Lectures

Moll:

In '52 I came as a Ph.D. graduate in electrical engineering from Ohio State, and I came to Bell. And within about six months of being there, I became what you might call a project leader trying to develop a useful device from some combinations of junction transistors, which I'll tell you a little bit more about later, but not now. I'll tell you the context. I had a group of about eight people, and I had information access that people, I think, can't dream about in technology today. Because I could walk down the hall, and I'd go into the office of a world-class physical chemist or metallurgist or whatever, and I could discuss specifically what my problem was. And we could discuss it on my terms, and we got enough metallurgy done in a new field, enough physical chemistry done in a new field, that had never been explored before, that we could carry on the development. And I don't think that very many people can understand that access to information. When people talk about today - and I'll be a little bit cynical maybe about television on demand - I say, well, we should talk about information on demand. And I must say that I've been on a sort of a downward slope from that day of information on demand.

I was at Stanford for 12 years, and of course we had a very good library and good access to other libraries in the U.S. Here the libraries are reasonably good, and we're trying to get better electronic libraries on the computer networks. But we haven't quite gotten to the point yet that I find satisfying. So that's a comment on current technology. We still have to catch up with what we were 50 years ago. But of these people, I stayed very close to Nick Holonyak. He went to the University of Illinois as a professor. He is still there, and he has contributed a great deal to optoelectronics, to the material and device work.

Goldstein:

You began working with him at Bell?

Moll:

He worked for me at Bell, right. We decided about two years ago that if we didn't try to write some history of what went on, that people would never know how silicon technology began. Because that's where the present-day technology really began. I really got started in this almost two years ago when I gave a talk at MIT in their VLSI Series about the beginnings of silicon technology. And I had to gather some things together. That was videotaped. Some people here at HP saw the videotape, and so it became part of a series. And we start series and then drop them, start them and drop them. But as part of the beginning of that series, I brought that a little bit further up to date and talked about the beginning of silicon technology.

Last fall I was asked to go to Tokyo. A student of mine was retiring, and he was the Dean of the College of Engineering at Tokyo University. And to have your ex-professor there, particularly from the U.S., was certainly something that he wanted. And he got the University of Tokyo to appoint me as a visiting scholar. And so they paid my way over and back. I felt kind of bad about taking all the money because I really visited other places besides the University of Tokyo. But as part of that, I gave several talks, one about the state of physics that surrounded the invention of the transistor, and one about the beginning of the silicon technology. The junction transistor had to be invented first before the decisions could be made of what semiconductor to use and what kinds of things to do. I'm sort of in the middle of trying to write that down. Maybe one third is done. I've also agreed to give that talk again in June as a lecture. And again, every time I do it it's a little bit different. I've also agreed to give it to a group of people at Precision Monolithics. We have an engineer from there who heard the talk, and he wants his people to hear it.

Goldstein:

If you have a copy of it, it might be useful for me to look through.

Moll:

Yes, I have the slides. I don't have words to go with all the slides.

Goldstein:

I see. You do it off the cuff?

Moll:

Yes. But I'm using this as, in a sense, an outline to write from. Well, Bell was one of the companies that was most interested in building semiconductor switches as well as amplifiers. I think that there was a realization that we needed a better amplifier. But also the Bell System is and was as dependent on the switches as the computer industry. So in retrospect, I can see that all of the requirements of a central office are contained in a computer, and vice versa.

Goldstein:

I think Bell's first application of the transistor may have been for switching rather than amplification. I'm not sure if that's so.

Moll:

Well, I'm not sure. I think that there was some effort to put this into an undersea cable. There were certainly a lot of directions that things were going in at the time. I was given the job of making a substitute for a relay. And there were two candidates at the time, as I recall. One was a gas tube. And the characteristics of the gas tube are that when it's off, it is a very high impedance. Then when you strike an arc, it's a low impedance, but it's very noisy. There is a merged n-p-n/p-n-p junction transistor structure which has that same characteristic, but it's not noisy. And that was my problem, what I was supposed to try to find.

Goldstein:

Was that your first assignment at Bell when you came there?

Moll:

Well, that came about six months after I was at Bell. I was working really at understanding the switching properties of the junction transistor before that. And it was before that that the Ebers-Moll Equations came. And through this there were a number of other papers that kept coming from understanding the behavior of various kinds of junction devices. So, I guess the Ebers-Moll was the first one.

RCA

Goldstein:

Before you got started with Bell you spent some time working at RCA after you graduated from Ohio State with a bachelor's degree in physics. What were you working on there?

Moll:

Well, I was working on magnetrons for radar jamming purposes. The major project was going on at Columbia University, and I think they were connected with the MIT Rad Lab at the time. I got into Columbia but never to MIT at that time.

Goldstein:

And what sort of things were you doing? I mean with that bachelor's degree in physics, what you were able to contribute to an engineering project?

Moll:

There were some problems that now seem almost ridiculous. But one was to help design the microwave resonators and the sizes of the cathode and anode magnetic field to get the right operating voltages and, hopefully, power, even though we didn't understand the efficiency well enough. It was a very efficient microwave generator, but we didn't necessarily understand exactly why. We knew how to get most of the device properties, how to design them. And my Ph.D. thesis at Ohio State University was really sort of related to that. That was, at least in part, because I didn't have access to any other advice. And you really need some advice, I think, when you're in the Ph.D. phase.

Goldstein:

Had you always planned to get a Ph.D.? Did you feel at liberty to do it once the war ended?

Moll:

Oh, I had assumed that I would get a Ph.D. I grew up on a farm, and at a very early age I had decided that I would become either an engineer or a scientist.

Goldstein:

Why did you go to work for RCA rather than continue straight through?

Moll:

This was the middle of the war. And, well, you either got into one of the war efforts somewhere, or else you went off to the army. Maybe I should have gone to the army, but I didn't. It's hard to say where you do the most good. Well, in the army I probably would have been in one of the officer training things because I had been in ROTC at Ohio State. Well anyhow, that's the way it happened.

Crystals, Germanium, Silicon and Diffusions

Goldstein:

So you were saying that you came to Bell, and you were charged with the responsibility of designing Electronic Relays.

Moll:

Now, there was a very important decision, I feel, that had been made in the development work at Bell, and that was that we would work with single crystals. It's my impression, even though I have never talked to Jack Morton about it - and he's dead - that Jack Morton pushed in the direction of single crystals.

Goldstein:

I spoke with Gordon Teal who grew the first single crystals of germanium and then later silicon. He said that he sold Morton on that idea.

Moll:

Well, that could be the case, yes. But the single crystal saved a lot of time. It would have taken us maybe five years or ten years maybe to realize that we couldn't do what we wanted to do with poly crystals. There was a lot of work going on. The technology in germanium was way ahead of that in silicon. And the germanium material was much better. But I had some idea of what the operating requirements needed to be, and they couldn't be done with germanium. And from everything that I could calculate, they could be done with silicon.

Goldstein:

You mean things like the melting point? Things deriving from the high melting point of silicon?

Moll:

Actually from the band gap between conduction and valence span. It's too small in germanium. When you wanted lines to be isolated, you wouldn't want the switch to be turned off. But the leakage current through the germanium device was too much. And it looked like it was actually way beyond what they required in silicon, but I naturally tried to keep it from being pushed too far. But this difference in band gap is the thing that made me want to go to silicon. And at this point in time I wrote an internal memorandum in which I pointed out these differences, and the inability of germanium to do a high impedance switching problem. And again, I feel very good about the management at Bell, because they read that. And they understood it, and they believed it. So I had good support.

Goldstein:

Did people contemplate other ways to handle the problem of leakage current? Might there have been just other approaches to this rather than try to get involved with silicon?

Moll:

Well, the only way that one could think of would be to refrigerate it below room temperature, and nobody yet has done that. In fact I think, as it turns out, there were a number of lucky things about silicon. There was one thing that I worried about silicon, was the toughness of silicon oxide, which turns out to be a benefit.

Goldstein:

You thought it would be unworkable because of it?

Moll:

Well, I didn't think it would be unworkable, but I knew that we would have to go to a very strong acid to remove it. And it's very hard to start a chemical process, a metallurgical process, on the silicon unless you remove the native oxide. So people said, well, you can't use - the hydrofluoric acid is just too dangerous. But we did hydrofluoric acid because that was the only thing that anyone knew of that would dissolve the silicon oxide. We still use hydrofluoric acid.

Goldstein:

And it was the strength of your conviction that silicon was the right material that prompted you to tackle this tough problem of getting rid of the oxide?

Moll:

Oh, there was a whole list of things. I knew they weren't killers, but I knew that they were difficult. The ordinary transistor is a two-junction device. The relay replacement is a three-junction device with the three junctions interacting. And I could not make this with alloy because when you alloy a junction, you alloy a metal and then recrystalize a little bit of the semiconductor. But you basically ruin the crystal. So I had to put a junction in without ruining the crystal. And so we had to do diffusion.

Goldstein:

My question here is, didn't Bell have this grown-junction process?

Moll:

Yes.

Goldstein:

And why was that not useful?

Moll:

Because it makes very poor use of a crystal. When you grow the n-p-n or the p-n-p, or you might learn how to grow another junction, but you get one slice when you get devices.

And well, I decided - rightly or wrongly, and it turned out rightly - that I had to make better use of the crystal. I had to be able to slice out a portion, and I sliced out as many slices as I could and made devices from the slices.

Goldstein:

So you were thinking in terms of the manufacturing, how is this going to be economical for the process?

Moll:

Well, it had to go in that direction.

Goldstein:

But alloy transistors are used now. How does that get around the ruined-crystal problem?

Moll:

Oh, you can make a junction, and ahead of the alloy the crystal is not ruined. But behind where you've alloyed and regrown the crystal, basically the crystal is ruined. And for two junctions that's okay, if you go from opposite sides of a chip.

Goldstein:

Right.

Moll:

But for three junctions, I couldn't do that.

Goldstein:

Okay.

Moll:

So I had to put at least one junction in by diffusion. We had to control the impurity of the diffusion. Diffusion existed at that time in silicon, in the solar cell. Gerald Pierson, who is credited as the inventor of the solar cell, had done his solar cells with diffusion. He had made a junction just underneath the surface which he did by diffusion.

Goldstein:

When was that?

Moll:

That was in about 1950. We knew about diffusion in silicon. The diffused-base transistor I think might have existed in germanium. But of course the technology in germanium is all at a lower temperature, and, as I say, it was several years ahead.

So we had to, in a sense, invent the diffused-base. We decided we had to do both the p-n-p and the n-p-n separately so that we would understand what was going into that structure. So the first diffused-base was, in fact, a p-n-p, and that was, at least in part, because the phosphorous is one of the most easily controlled diffusants. We had sort of on loan a person, Carl Frasch, who was doing the diffusion. And I think because we were young and enthusiastic, Carl worked hard for us. But in that process, he really discovered the masked diffusion that you could get from oxide. He discovered wet diffusions which helped us to control the crystal, and later on masked diffusions. I'll tell you how the wet diffusion came in. All we would do is that we would diffuse for a short time at a high temperature, and then we'd take the crystal out and put it in a tube and drive it in, do a "drive-in." That was the way we were intending to control the amount of diffusants at a lower level than, say, solid solubility. But usually Carl would come with a very sad look on his face and say, "Well, we've lost the crystals, we've lost the wafers." He was doing sealed-tube diffusions. And if there was a slight temperature gradient in something that would react with the silicon, it would just act almost like chlorine does on the ozone. It just kept working on taking that single crystal, and putting it at the coldest part of the tube, and you'd see a pile of dust in the coldest part of the tube. And we were trying all kinds of things from the periodic table as the ambient gas. I don't know how this happened but either a flashback of hydrogen occurred because they didn't seal off the quartz tube with the hydrogen torch, and that put some water vapor in, or somehow he got some water vapor in the tube, but the resulting crystal was beautiful. It had oxide that was growing on it. You etch off the oxide, the crystal was mirror smooth, and our problems are solved. That problem was totally solved. It was either by intent or by accident. I don't know. But it doesn't make much difference if you're smart enough to know what you're seeing. So probably that processing Carl Frasch did - see, that was patented. And as I understand, at one time there were 160 companies that were licensees to that patent.

AT&T Licensing and Patents

That's interesting. Do you know anything about why AT&T had licensed the process rather than kept it proprietary?

Moll:

Oh, the attitude there at AT&T was that it was desirable to have as much as the industry working on semiconductors as possible. And it's quite a different attitude than today when AT&T is trying to be an entrepreneurial company. At that time we were really a regulated monopoly. There was no danger of anyone moving in on the telephone business and taking it away on the one hand. On the other there was a lot to be gained by having very reliable, well-understood components in the system so that they would last a long time. In some cases Western Electric would make vacuum tubes, with the same numbers as private companies. But because they went into the telephone system, they were more careful in the constructions, and they could afford to have their own factory to make these tubes because they would last longer. If they cost twice as much and last twice as long, they would be cheaper because you wouldn't have to change them as often. And changing something or repairing it always costs more than putting it in in the beginning. So it was quite a different attitude. And in spite of being a monopoly, we were proud of the fact that we had the best telephone system in the world. Monopoly or not, it was the best one in the world.

Goldstein:

Right. Were the scientists at Bell Labs involved in assessing the economic considerations of a new technology? You say at AT&T, that they believed it was better to promote the growth of this technology. Was that always the overriding perspective? Or were there some technologies where scientists might suggest that nobody is even close and we're giving away the store to lease this information?

Moll:

There may have been such things, but generally the scientists like to talk about what they're doing. So this, I think, probably also was beneficial to the general environment. We could write papers and at least discuss them in a general way, in enough detail so that an intelligent person could look at that and probably repeat the experiment. So we felt good about it.

Goldstein:

I know that AT&T had a patent department that would suggest what should be patented. So if that wasn't up to the scientists' initiative, I was just wondering to what extent the scientists played in considering how AT&T could best profit from the work they were doing.

Moll:

Yes. This was extremely variable. See, I went there without any idea of what patents were all about. So I didn't personally look for things to be patented. There were people who had that as a very high priority of getting patents. So it was very much an individual thing. And I guess we all were pretty naive about patents. But after about two or three years at Bell, Nick could have been deferred, but he didn't want to be deferred, and he was in the army, and he was stationed in Japan. And he got to know some of the Japanese people, particularly at Sony. He went through sort of an exit interview, and one thing the patent department told him is that in Japan he should never talk about the masked diffusion that we were doing with Carl Frasch. So there was some consideration, I guess, at least in the patent department.

Goldstein:

License was only domestic? I mean if the process was licensed to 160 companies, they were all American?

Moll:

Well, let's see. I have read about the co-founder of Sony. What's his name? He wrote a book about Japanese and American technology. He had some problems in convincing the board of directors that they should license the transistor, but they did. So Sony licensed that transistor process, and of course they really needed it if they were going to build the pocket radios. So I know that there was some licensing in Japan at an early stage. I don't know any details of the license. It may not have been for silicon; it may have only been germanium in the beginning. There are all kinds of licenses. So anyhow, I guess nowadays it would probably be a two-way agreement because Sony has done some good technology.

So, Bill Shockley left. Well, he really wasn't around Bell very much at any time that I was there. I saw him a few times, but not very often. But he left officially to form Shockley Labs in 1958. And he tried to recruit people from Bell, but he was not successful. He did recruit some very good people nevertheless. But he was in almost daily contact with Jim Goldie, who was another one of the people working for me, and he was getting the diffused-base process from us almost like a cookbook. Now, Jim was kind of worried about that, that if we are giving out everything that we've struggled to get in almost cookbook form; which meant that it would save an awful lot of time on how you do it. Even the cleans and etches and things like that. He knew exactly how much of this or that. And if it was a different temperature then room temperature, what temperature. We checked with the management at Bell, and they said, "Yes. Go ahead and help him." And I think there was a certain amount of-- Well, Shockley left in a friendly way, and so there was an attempt to help him. But that was sort of the basis of the technology that Shockley got started, and then got moved to Fairchild. See, Shockley was trying to build that three-layer diode, which was a relay. And he was scared, actually, of competing with Texas Instruments because Texas Instruments was doing grown-junction silicon transistors. They were ahead in the business. But I guess Noyce and Moore were a little bit more daring, and they were better managers of people, in fact. And they thought that they had their hands on a better technology, so they started Fairchild. And a lot of things were added beyond what we did. It's been in the direction of diffused junctions, in some cases diffused base and diffused emitter to get better control of the emitter for the bipolar device. Now the huge growth of the integrated-circuit market is really based on the MOS device. So I guess we would never have gotten here without something like MOS, and probably complementary MOS.

Working in Material Science

Goldstein:

The work you're describing is very much in material science. You've worked on device fabrication. I wonder what prepared you to get involved with that. Sounds like it's a far cry from what you were doing at Ohio State.

Moll:

Well, I don't know. Maybe I shouldn't have done it. This is a comment that Nick has made is that he never realized how important the materials were until he got into that group.

Goldstein:

Well, was it tough going for a while, learning some of the interdependencies?

Moll:

Well, at Ohio State I took almost every course that I found interesting. And I tried to avoid everything that I didn't find interesting. So I took almost all the physics courses, and all of the math courses. I started as a Ph.D. student in math, and if my advisor hadn't died midway, I might have ended up teaching mathematics at some university. But the math professors were fighting among each other, and so I ended up with a more friendly person in electrical engineering who wasn't fighting everybody. So that's why I got the Ph.D. in electrical engineering. But I guess my engineering sort of spanned everything. I didn't take very much chemistry or material science, for that matter. But whether you have courses in it or not, you can be exposed to those needs. And, as I have mentioned about Bell Labs at that time, they had material scientists, and they were interested in my problem, and I could discuss material science. And I probably learned it faster from them than I would have in a course.

Goldstein:

I see. What was your role in this effort? You were the leader of the team?

Moll:

Yes.

Goldstein:

And did the composition of the team change over time?

Moll:

Very little, and not for a period of about three or four years, I guess, where we were pushing the silicon technology. And when I look at it, it just went at a rate that is unbelievable now that you would never accomplish that much in that time. But we were very highly focused. We would have lunch, not every day, but maybe at least a couple of times a week, maybe more. And if somebody was doing something that might be interesting to the group, I'd try to arrange that we would go and see it. The topic that we focused on was the technology that we needed to get that device. And every [so] often, if we talked about something on Monday, that or something very similar to it would show up in an experiment the very same week - maybe even the same day - so that the turnaround from ideas to experiment is very short, and the concentration of mental energy was very high. We avoided doing things that were distracting. And I think that Nick will tell you that he had lots of ideas that I kept him from trying.

Goldstein:

I was just thinking that. That if you stay highly focused then you can't follow up on all the interesting, unexpected results when they pop up. Was there any effort to revisit some of those interesting ideas, to get back later on that?

Moll:

No. There was so much progress that there was no point. Nick had some ideas that we already had: the germanium technology that he could, in a matter of weeks, get devices like we were trying to build. And I told him if I had it in germanium, I would not give it to the circuits people. I wouldn't give it to anybody because its characteristics wouldn't be good enough. And I guess I would sit down and talk to him long enough until he believed the physics of characteristics of the situation and would work on silicon technology. Now, if we had done that, see, he would not have been able to do the work in silicon. Yet maybe not in two weeks but in 20 weeks, he would get something better in silicon. And he'd realize that there was no point in doing it in germanium because he had something better.

Goldstein:

I know that AT&T built a facility in Allentown to make the germanium transistors. They were even making the point-contact ones. Do you have any idea what they were being used for? I mean you said that you wouldn't give germanium transistors to the circuits people, but they did use some.

Moll:

Oh, the germanium is perfectly adequate as a two-terminal amplifier, and it could even be used in some applications today, except that the silicon technology is so much further ahead that germanium would be more expensive now. So it's not that germanium isn't good for anything. In fact there's even some semiconductors with narrower bands, the band gap, in germanium will probably find use in optoelectronic applications. But when you come to, say, a switching application, I think if anything you might even go to a wider band gap, not a narrower band gap. But the silicon is perfectly adequate, and it's so for ahead of anything else that I don't see that it can be killed. I mean it's sort of like the automobile. You change some of the steel to plastic, you change something, but it still is the automobile. And there's no point in changing a microprocessor. Why should you try to make that out of something else? You can almost make a supercomputer right now on a single chip. Intel is selling the Pentium for under a thousand dollars and it has about three million transistors on it. And it's not the end of the road.

Management and the Question of R&D

Goldstein:

What was Nick's position at Bell relative to yours?

Moll:

Well, he was in my group.

Goldstein:

You see I just don't have any sense of the organization of your group. I don't know if he was in charge of a few people working under him.

Moll:

Well, no. I would have members of staff, and to the extent that we could support them with technicians, why, they would have a technician.

Goldstein:

Was that unusual, for you to come to Bell and be put in charge of a group that way? It seems like you rose to some management level immediately. That you were just inserted in management.

Moll:

No, there were six months before I was. I was told by either Gene Anderson or Jack Morton that a lot of people would be watching for me because they were paying me more than almost any other person got paid as new Ph.D. I was getting all of $6400 a year. But I guess that was a high salary at that time. Well, it certainly looked high to me.

Goldstein:

Do you know what that is? Why you were so well-esteemed?

Moll:

Well, I had a pretty good record in the university. Bell's was not the highest offer that I had. I had lots of other offers. But that was a time when everyone was expanding. So that wasn't unusual. Everybody would have good offers. But I guess this was a case where Jack Morton was personally going out and recruiting people for the Department 20, or Section 20, or whatever it was, which had sort of the general objective of taking the things that were invented, or seemed that they might have some use, and turning them into practical things for AT&T. So that was the general thing. I suppose that specifically you would say that, well, you shouldn't be doing research there. And as I look back, there were a lot of very good research types of things that happened there. But when you take things at such an early phase, when there were so many questions to fill in, whether it was development or whether it was pure research, there were always good research questions.

Goldstein:

Did people at Bell concern themselves too much with that question? You see in the historical literature all the time: Was it research? Was it development? And I just wondered whether the scientists or the management at Bell cared about that question.

Moll:

Well, I never cared. But still I think that some of the papers that I have would represent very good research efforts. They're representative of good research efforts.

Goldstein:

A lot of the work that you did is highly theoretical. For instance you were saying that you explained to Nick from the physics perspective why silicon was preferable. My question is, was there room for people to work less theoretically, and to develop a manual skill with materials? Was there room to contribute in those ways?

Moll:

Well, we absolutely had to have those kinds of people at least in the support of the technicians - in support of the MTS's - the technicians that were supporting MTS's. But we had members of staff that were really very practical people.

Joe Klimack

He was not in my group, but there's a fellow, Joe Klimack. He smoked himself to an early death. He didn't understand theoretical things, but he was very good at doing things.

Goldstein:

Real strong intuition?

Moll:

And he was a member of staff. I have sometimes described that as an inverted pyramid when there is Joe Klimack, and then all of the structure of Bell Labs making promises on the basis of the transistors that Joe Klimack was making.

Goldstein:

That's interesting. What was Klimack's position? Who did he work for?

Moll:

He worked for Jim Ebers.

Goldstein:

What sort of things did he work on? You know, what did his particular skills give him an advantage in doing?

Moll:

He was working mostly on germanium transistors. He helped build furnaces to do the alloy transistor, which was what he was doing. And I still remember him looking through a microscope, and a cigarette in his mouth, and ashes falling over the transistor. But still, what he did was better than anyone else could do. And he understood enough of why it worked that he could teach other people.

Goldstein:

There's in your voice, I can hear, respect for him. Was that universal then?

Moll:

It was among the people that knew him. Bell Labs was a big place, and people in the theoretical, or the physics or chemistry department might not have known him. So they wouldn't have known whether to respect him or not, I think. The people who knew him had good respect for him.

Goldstein:

Right. I meant it actually as an example of somebody with a less masterful theoretical grasp.

Moll:

No, there was, I think, at least most of the people realized that we needed Joe Klimack to help us.

Tubes and Solid-State Analogies

Goldstein:

I've heard it said that there was at Bell in the early fifties - now what's the term they use? - new art and old art. And tubes were regarded as old art and discouraged heavily. Were you sensitive to that?

Moll:

I don't even know anybody that was working in vacuum tubes at Bell.

Goldstein:

Really! I'm interested in the analogous role between solid-state and tubes. Did people rely on analogies? You know, “the transistor is simply a vacuum tube that's made out of a semiconductor?”

Moll:

What I considered to be the first serious proposal that I’d seen in writing for a solid-state triode was from Bill Shockley. And this was definitely an analog to a vacuum triode. In fact the very first drawing that he ever put down had grids in it, and it had the Schottky barriers instead of fields in a vacuum. But it would modulate the current that could flow between the grids, just like the fields in a vacuum do. And he made a modification of that very shortly after which might be easier to build. But nevertheless, that was what people were working on. In fact, if you go back to the very first impractical ones that wouldn't work for sure, you would find that they were all analogs of the vacuum triode. And then you come - Well, in Bill Shockley's case, it was puzzling that that didn't work. It should have worked, but it didn't work. And that was one thing that led to the invention of the carrier injection transistor, which was the point-contact, was experiments to try to understand why that didn't work. And in the process John Bardeen discovered surface states and explained what was going on in surface states. And after a whole series of experiments, he and Brattain became suspicious that carrier injection was happening in some of the experiments. So they built a point-contact, and the very first experiment worked as a carrier injection device. Now, not everybody believed that, but Bardeen did, and it was his thinking that way that led to that discovery. So I think you have to give him credit for that. I don't think anyone argues with that. Well, there are some people that do, but they don't understand what the physical problems were and the physical thinking that was going on.

Goldstein:

So years later, are you still thinking in terms of an analogy?

Moll:

No.

Goldstein:

How did it die, the recognition that, you know, the minority carriers are important, things like this?

Moll:

Well, the discovery of the point-contact in Bardeen's explanation, which, as I say, people didn't quite believe, as a carrier injection device, occurred in December of 1947. John Shrive did an experiment in January of 1948. This was fairly definitive in proving that what they had was a balky factor that was happening through the crystal and not on the surface. Bardeen had published a paper on surface states about a year before in 1946, I think, in which he explained surface states. So people thought that it might be surface states. But if you look at the results, the polarities were all wrong, the controls were in the wrong direction for it to be surface states. Also Bardeen had had this suspicion beforehand, that it was injection. Shockley had been trying to think about experiments which were definitive, which would show what was happening; in the process he actually invented the junction transistor. So it was about 1950 that the first junction transistor was built. That was a go-junction transistor.

Technology Evolution, Integrated Circuits

And then from '50 to, well, I don't know how long. It might have been '55, it might have been longer than that. It was almost like there was a new device, a new technology, every month. There was a space history that came out of Raytheon. There was the jet-etched transistor from Philco. There's any number of things. I was lucky in a way in that I didn't try to invent new things, but I saw that what we needed was proper technology for the junction transistor. And what we did was, I would say, was really the basis of how Silicon Valley got started. In 1970 I worked for a couple of years at Fairchild, '70 to '73 or '74, something like that. I consulted with the discrete device people there, and they were using almost the same technology that we were using at Bell. It had advanced a wee bit, but just a wee bit, from what we were doing at Bell.

Goldstein:

The situation you're describing is almost a classical picture of evolution. There are a number of different competing technologies, and one emerged dominant you're saying. Can you account for why the diffusion triumphed?

Moll:

Oh, yes. First of all, essential to this is the addition of the invention of the integrated circuit. Which means that you leave the oxide on, which actually other people had suggested. Carl Frasch had said, “well, maybe we can leave the oxide on.” But you leave the oxide on, you just make a hole down to where you want to make contact, and you wire from that contact to some other hole where you want to connect to. And the very first integrated circuit was a single transistor and a single resistor. So that it was two devices in a package instead of one. But it made much simpler a certain kind of logic - half the number of components. And it went on from there, of course, to millions and millions of devices. And it's almost like the technology of choice is the one where you can put, say, a million or two million devices in a circuit and make the connections. And whether it's basically faster or not, the fact that you can put two million of them on a single chip makes it faster.

Goldstein:

What was Frasch thinking about when he suggested leaving the oxide on? Was he thinking integrated circuits?

Moll:

No, it was about 1960, I think, when we first began to think about integrated circuits.

Yes, but that was pretty crude, and probably wouldn't have worked. Because, in fact, what he has in his patent won't work.

Goldstein:

Really?

Moll:

He has gold connections, and they won't work. And I think his demonstration was little gold wires.

Goldstein:

So what did Frasch have in mind when he suggested leaving the oxide on?

Moll:

Well, that you could - It would be easier to make the contact to a junction if you could open up the junction and leave the oxide over the edge of the junction. Then you can put down metal without shorting the junction.

Goldstein:

Okay.

Moll:

But, see, we did not have photolithography at that time. It was some years later that that became sort of useful. So there's just any number of things that have been added, but this is the mode that silicon has gotten into, is that you add things, and what you have becomes a little bit better. And the result is that there are enough people working in that, and it's so far ahead, that it's almost impossible to jump in and do anything better where silicon is good, namely being a switch.

Charge Control and Ebers-Moll Equations

Goldstein:

I read, not long ago, that some people thought that the transistor was a charge-control device. Do you know anything about that?

Moll:

Oh, yes. See, the Ebers-Moll Equations could be written as charge control. I think that- Well, it may have come out simpler, but then maybe not, if it had been written as charge control. But that's a perfectly reasonable way of looking at the device, as charge control. The bipolar device, that is. That you inject charge into the base, and it sits there, and current flows between the emitter and the collector. You can move the charge, and the current stops flowing.

Goldstein:

But that wasn't the perspective you had when you worked on the Ebers-Moll Equations?

Moll:

I wasn't thinking in that way, even though we were very well aware of the charge storage in the devices. And in fact, a sort of adjunct to that, I did some things which showed the switching properties which were based on the charge storage. So it's not far away. I mean the charge control and this model are not far from each other.

Goldstein:

How would you characterize the model?

Moll:

Well, it's a mathematical way of describing the electrical behavior of a [Unintelligible Passage] device.

Goldstein:

If it's not in terms of charge, is it in terms of field?

Moll:

It's in terms of currents and end voltages. If we'd gone a step further and integrated the charges in and out, and recombined, why, it would be charge control. But I guess, well, we chose to do it the way we did.

Goldstein:

Consciously? I mean, did you make the selection?

Moll:

I guess I did it that way because I thought it was an easy way to understand what was going on.

Goldstein:

What sort of work led up to the Ebers-Moll Equations? What were you trying to get done, and how did you go about it?

Moll:

What we were trying to do was to get a simple enough explanation so that the people that are doing circuit design or circuit applications could understand this device, as well as they could understand, say, a vacuum tube, which most of them grew up with. It looks theoretical, but it was really very much an engineering application.

Goldstein:

Did you work theoretically or collect a lot of data? Do a lot of measurements of known parameters?

Moll:

I worked theoretically. And if I came to something that looked a little bit strange, then I would go out and make some measurements. Shockley did earlier work, but none of these ever worked because he was using copper oxide.

Goldstein:

Yes, he has an article about this that was published in 1976.

Moll:

And I think it probably is something on the copper oxide. But it's hard to understand why it won't work. There's also Shrive's experiment. This is the thing that would substitute for a mechanical relay.

Circuit Issues and Contenders

Goldstein:

When did you produce one that you were satisfied with, that you could turn over to the circuits people?

Moll:

Oh, it was somewhere around 1958 that we started to give just a few. And of course we found out that in big circuits this had some problems. And this is not used very much; it might be used a little bit, but not significantly.

Goldstein:

What sort of problems? What was happening?

Moll:

Well, there were characteristics that we hadn't thought of when we started. Like capacitor feed-through, which sometimes would turn parts of the circuit on when you didn't want it to happen.

Goldstein:

So what did you do?

Moll:

Well, we had to go back and rethink the circuits. Of course there are now electrical central offices, and I don't know how they're built. I think they're probably built in different ways than this.

Goldstein:

So when you say you think the circuits- You retained the device and redesigned the circuit around its characteristics?

Moll:

Well, at that time the world was wide open. That device wasn't necessarily the winner in the contest to be the switching device in the central office.

Goldstein:

What were some of the other contenders?

Moll:

Well, as I say, the gas tube was a contender. The possibility of just using a switch where you could control it externally. In this case the idea was that you would just put voltages across the two terminals that you want to connect, and it would connect itself through the cross points. And I think that right now the cross points are controlled externally and not in that simple way. But that seemed like a simple way to open and close the cross points.

Goldstein:

I thought that when you turned your back on gas tubes in favor of solid state that was it for gas tubes. But other people were still working on it?

Moll:

Yes. And the people that were building central offices were working - and have continued to work - on whatever technology looks best. And now because large integrated circuits are easily obtainable, I would think that they sure would use large integrated circuits for the switching part of the circuit. This was being down at Whippany in New Jersey, which was about ten miles from Murray Hill, where the materials and device work was happening. So it was close enough that we could talk to each other once in a while. That's what the cross section of an alloyed transistor looks like [Shows Illustration]. You see there is some crystal back there, but you can't count on that. You see that one has the same control as the previous ones. And it looks like the other two sides are connected, but they're not. See those are the two sides. So we had very poor control compared to what we needed. But there's a list. That was what we were faced with.

Solving Problems, Lifetime Degradation

Goldstein:

Well, we haven't talked about diffused junctions, controlled impurity density, aluminum and gold, antimony arsenic thin films, lifetime degradation, or crystal imperfections. Did you have different people working on each of these problems? When you started, did you have an idea about how to solve each of these problems?

Moll:

We thought we knew how to do the first four. And lifetime degradation, we knew it happened, and we didn't know why. No one knew why.

Goldstein:

Is this the problem?

Moll:

Yes. And somebody told me a few days ago that he had died a few years ago. George Bensky was trying to understand this. And I guess in retrospect I sort of stumbled onto the right things with the [right] people. What we did was we said, well, we'll start out by learning how to measure the crystal lifetime as it goes through the process. And so we concentrated on that. Well, my idea was, well, "we'll see what kind of processing the crystal can take without suffering from too much loss of lifetime." But George made a discovery that if you would evaporate nickel on the crystal after the lifetime was degraded, then unless it's above the eutectic point, nickel by itself will melt at something like 1200º, I think. Silicon by itself will melt at 400º. But a mixture of nickel and gold, the right mixture, will melt at 950º. And this minimum point is called the eutectic point. Then the lifetime came back. And so it didn't take too many experiments to decide that what was really happening was that we were a process like that gettering [that] was going on.

Now, gettering in vacuum tube terminology means that you remove the things from the vacuum envelope that you don't want. And in this case we were removing this from the crystal that we don't want. They were going out into the liquid mixture. This process has stayed in one form or another with silicon processing ever since. Of course we find that almost anything will act as a getter if it's used right, if it forms even a solid glassy mixture, it will act as a getter. So, for example, phosphorous glass has a relatively low melting point. But this acts like a getter. And there are a number of other things that one can put into a process that will act in this way. But it all started with George Bensky. So I think that to me was a very miraculous discovery, that he could remove most of the bad things that were going on. We set things up to measure, and we found out a few things. But we really were not able to do very much about the surface. We would try to count the dislocations per square centimeter. And if they were too high, we knew that we couldn't build anything. But at the present time, people can build slices that are this big in diameter, that have almost no imperfections. And if we had 105 per square centimeter, then we could make the things that we were making.

Goldstein:

That was pretty optimistic to get started with silicon, given that list of issues.

Moll:

Yes. We knew that we didn't have to solve these absolutely. We just had to understand well enough what was going on. This one was a tough one. We knew that we had to do something about that.

Goldstein:

The lifetime degradation?

Moll:

Yes. Right. And I was pretty confident about being able to take care of these. See, Nick Holonyak was doing that and working with Carl Frasch. And Jim Goldie was doing this and also working with Carl. And Carl Frasch was doing most of this process.

Goldstein:

Diffused junctions and controlled impurity density?

Moll:

Yes. Right. And George Bensky was doing that.

Goldstein:

The gold thin films?

Moll:

Yes.

Goldstein:

Was anybody at Bell discouraged by that list?

Moll:

No. I never showed anybody the list. But, no.

Semi-Reorganization and Silicon

After a couple of years now - and I can't prove this; Nick Holonyak tells me that it's true, and it may be true, and I don't know - that Jack Morton was called back from a trip because they were in the process of a semi-reorganization.

Goldstein:

About when? What year?

Moll:

This was in about 1954.

Goldstein:

Okay.

Moll:

And we had been making such good progress on silicon, that they were switching a lot of the development effort from germanium to silicon. And this was something that Jack had to approve. But without solving all of these, I think we got through- we got down to this part. We got past this point. We had done so much that they decided that they could afford to put their eggs in the silicon basket.

Goldstein:

Who above you would you talk to about that?

Moll:

Well, it would be Gene Anderson.

Goldstein:

I see.

Moll:

And Nick likes to tell a story about Joe Klimack. He says, "Joe thought we were a bunch of liars" because he didn't think anybody could make progress like we were. But after he and Nick worked together for about a week, why, he said, "Well, you guys are right." See what I do is I go through these to sort of give a progress report after every two years of saying what happened there. These look like simple things nowadays. But we didn't have any standard methods of cleaning. Nothing was standard. So we had to learn all of these things. And as I look at it, I think a lot of this came from discussions at lunch.

Universities and Industrial Labs, Publications

Goldstein:

Could you tell by looking at the published literature what other people were doing? And so can you describe the great progress you were making? Have any perspective on the progress at other places?

Moll:

I looked at universities, and there was no university that was doing anything that would help us. I look at what we are talking about in the United States now, and I wonder about the wisdom of saying, well, here we have these great resources of the universities and industrial labs that can make us industrially competitive. And particularly the government labs scare the hell out of me. They're not used to doing the kinds of things that you need to do in industry.

Goldstein:

Which things are they?

Moll:

Well, in some cases they're very good at solving physical problems. But in, say, well, to make this useful for industry, it has to be simple, it has to be ultimately heading for a low-cost manufacturing, and useful to people. They're not used to that. Their directions have been set by the military for so many years that either they're pointed in that direction, or else they have rebelled and refuse to consider any utility. This is my experience in talking to people. So the general idea that the government will do something is wrong. The government should get out of the way and let us do things. See, in this case the Bell management gave me adequate support, and that was enough. We just charged ahead. That was our equipment home built. And once we started to talk about diffused transistors, the vendors reported that they couldn't build enough of those things because there were so many people who wanted to at least reproduce the experiments.

Goldstein:

Other labs would call and ask for the equipment? How did publication work? Were you publishing frequently during this work?

Moll:

Reasonably so, yes. Mostly IEEE. See, I was concerned, as a matter of fact, that in the diffused transistor the impurity concentration was not constant. And everything, all the theory to that point, assumed a constant impurity concentration. There's a paper that I wrote with Ian Ross. Now, Ian became the president of Bell Labs. He was president of the company that put up a ComSat. And then he came back and was president of Bell Labs. But we found that we could talk together in a very good way, and exchange ideas. What we did was that we basically showed that the switching properties didn't depend on how the impurities were distributed in the base. And of course we were dealing entirely with the injection devices at that time. So Ian was in the research section, which although not in his case, I guess they felt that they were a little bit better than development types. But I managed to get over that in every case. Carl Thurmann was one of the top physical chemists in the world, and he and I had some very good discussions about the physical chemistry problems that we had. And he was in the research section. So whenever I had a problem, I was able to go anywhere.

Working in Research Section

Goldstein:

I want to move on now into the sixties. You said that by '58 you'd developed the p-n-p-n switch there. So what happened after that? What did you start working on?

Moll:

I spent about a year in the research section at Bell. Now we were doing typical research problems. I was a lab manager there. And then I suppose at least in part I might have done that just to show that you can go uphill, so to speak, in that society. But in part it was interesting because we were looking at various kinds of silicon problems to try to understand the way electrons behave in the crystal, and the way various junctions behaved, and methods of making junctions.

Goldstein:

It sounds like you were less focused on a device.

Moll:

I was not focused on a specific problem.

Goldstein:

How did that compare?

Moll:

I guess in retrospect the most exciting thing is to have a new problem in a relatively unplowed field and be extremely well focused so that you make lots of progress. And then you can look back and say, yes, you did that. So at least that's for me. See, I didn't care at the time whether it was research or not. Now, people look at that and say, well, you did a lot of research. Well, see, I didn't give a damn. Sure, that looks like research, but we were doing a practical problem. If there was a question that came in the way, even if it was just a doubt in your mind, that would hold you up. And so you had to get that out of the way. And if that looked like research, that was research.

Goldstein:

Was this a value of yours that you had before, [or] was this the Bell way, maybe the spirit of Mervyn Kelley?

Moll:

Oh, I think that it's very much individual, that. Well, it was individual, but it was also that I was in a general environment that allowed it. Now, of course in this environment at Hewlett Packard Labs, if I get interested in something, I can do it. But I don't know if everybody is like that. I've heard complaints that we don't do enough research. I've heard complaints from other companies that they don't do enough research. I guess I would have to be very close and very much acquainted with those circumstances. But my feeling is that if a person complains about not being able to do enough research, it's because he can't.

Goldstein:

It's hard to tell, though, whether that's a result of the nature of industrial research today - you know, whether that situation exists in all labs today - or whether it's a difference in corporate culture between Bell and Hewlett Packard.

Moll:

Yes. And for that reason I'm very hesitant to be too critical of anyone. But, yes. It might be that they are given so much work and such a short period of time to do it in, that there's no time to do research. That they have to get down to the bench and do something. Or start writing some computer programs or something. I don't know. See, my own personal way of working is such that when I need to do research, I do research. And I haven't had any problem at Hewlett Packard.

Stanford, MOS and Transistors

Goldstein:

So to continue the chronology, let’s discuss the early sixties.

Moll:

Then I went to Stanford. And I still was not very savvy about patents and things like that. But see, we did the first MOS diode at Stanford, the very first one that anyone had published on. It's possible that somebody at Bell had done one before that because I had some visitors, and I was telling them about the MOS diode and its behavior. And there's a very funny look on George Dacey's face. He was one of the visitors. And then when I was done, why, he told me that there's a fellow at Bell Labs that made such a device. Well, I guess I made the first report on it. But I wasn't quite smart enough to realize that that was the essential part of the MOS transistor. I sometimes kick myself. The MOS diode is really the gate and channel structure of an MOS transistor. But I wasn't quite smart enough, and somehow, even though we talked about it, the people around me didn't quite kick me in the right direction. I guess none of us were quite that patent-conscious or conscious of the value of the new structure.

Goldstein:

What got you to working with MOS to begin with?

Moll:

Well, at that time there were a lot of things that we didn't know about silicon. And we didn't know about how you could control a surface. We didn't know - when you had a diode, we didn't know what made it break down in the surface or in the balk. Usually it would break down at the surface. We didn't know how to prevent that. So there were just myriads of things that we didn't know. And I got started as the research part of my work at Stanford trying to understand, number one, the behavior of electrons in holes in high fields. That was one of the problems. And as part of that, I did things that were peripheral to that question of getting the structures to understand this. I used to ride my bicycle back and forth; I probably still should. That would help because I g[o]t ideas when I was riding on the bicycle. I'd be thinking about the experiments we were doing, and I'd think about that. And I said, well, why don't I just make an oxide and put an aluminum electrode on it, and see if I can find out what happens to the surface underneath? And of course I very quickly realized that I was getting an inversion layer. I remember Walter Brattain coming down and visiting, and I explained a little bit to a group that Walter was with. And he said, "Well, if you're getting an inversion layer, why, you've really got something." And of course Walter had been working with problems of getting inversion layers all his life. And he had been trying to make a transistor using that structure as the connection between source and drain. So I should have, in retrospect, maybe I should have caught him and said, "What have I got?" So I can think of a lot of things I did wrong.

Goldstein:

I'm not sure I understand. You used this aluminum- Your original goal was measurement, you were testing.

Moll:

Well, to understand the silicon surface.

Goldstein:

Right. And so you took out the aluminum as an experiment.

Moll:

I made an oxide and put an aluminum electrode down on the oxide.

Goldstein:

And then discovered accidentally, or unexpectedly-

Moll:

No, no. In analyzing what that was and measuring it, I found that I got an inversion layer. And from the electrical characteristics, well, you could pretty well intuitively guess what was happening. So that was the basis, then, of being able to make certain kinds of variable capacitors. It turns out that they aren't very good at high frequencies, but they are very good at analyzing what's going on in the silicon near the surface. So it's become a standard test part that people put in to test circuits to see what's happening in the silicon. But I was too dumb to realize that if I put in a source and drain that I would have a transistor.

Goldstein:

Were you working with anyone?

Moll:

I had some people around me who were device physics types of people. But I think none of them were quite experienced enough, they weren't quite attuned to the getting of new inventions. Which I also wasn't yet.

Goldstein:

You say "yet"?

Moll:

Well, I've learned maybe in the last five or ten years. I've seen all of the court cases over inventions and things like that. So I'm well aware now of what inventions mean. But I never paid much attention most of my life.

Goldstein:

Well, I really don't know the story yet. Who did prepare the transistor?

Moll:

The invention was obtained, correctly, by Dow and Kahn and John Attala at Bell Labs.

Goldstein:

Was this based on your results, or had they been working independently on the same thing?

Moll:

Because someone at Bell was doing this, they had his results.

Goldstein:

I see.

Moll:

I can't remember the name.

Goldstein:

But they were independent?

Moll:

There's someone in the metallurgy department [who] had done this, and I forget his name. Who had made the MOS structure and had observed some characteristics. Of course at Bell there were a lot more people to interact with, and it was likely that something would happen if it was going in the right direction.

Goldstein:

Do you have any idea why this person used aluminum. Were they looking to create an inversion?

Moll:

I don't know whether he used aluminum, but aluminum is a good material because it sticks to silicon dioxide.

Goldstein:

Right. It's simple.

Moll:

It's simple to use.

Goldstein:

But whatever the material, was the person looking to create an inversion layer specifically for the purpose?

Moll:

I don't know whether he was even doing that. And as a matter of fact, he was making a different device than I was, a device that- Well, I'm not even sure because he never published. But the patent was appropriately given to Attala and Kahn.

Goldstein:

Then what else? Why did you leave Bell to go to Stanford?

Moll:

Well, I knew that they were starting up semiconductor classes, and I thought that I wanted to go to a university and teach. And in fact I stayed there for 12 years. And that was a good period of my life.

Goldstein:

So it was a way of expanding. Not necessarily to different or better research, but to expand to teaching.

Moll:

Yes.

Goldstein:

Did teaching dominate your activities during this period? How much of your time was spent in instruction, how much in research?

Moll:

It was sort of half and half between teaching and research. And it was a good time to do research because you gave a reasonable description of what you wanted to do, and you could get it funded. I've seen what's happened now, the time that people spend. In fact, it was happening at the time I left. I didn't like it. People were just beginning to spend all their time selling research to the government. And they don't have enough time to do the research; they have to give it to graduate students. That's terrible.

Goldstein:

Where did you find most of your support coming from?

Moll:

Mostly from Fort Monmouth. I had people who had students who were doing what I thought at the time at least, and still think, was fairly good work in wrapping up some of the questions that were still up in the air when I left Bell. Like what happens in very high fields, and when does tunneling start in silicon, and such things at what fields. I had a student from Finland who did the first rational design theory for the MOS transistors. There was not such a theory, and in this case it was not the first publication, partly for political reasons. It got to the IEEE first, but it was rejected for some reason. I think because the wrong reviewers read it, and they wanted their man to be first. But I won't name any names in that, but that can happen. So it was the second. The report to the government by the Stanford report, was the first.

Goldstein:

Who got the report in first?

Moll:

Somebody from RCA. [Unintelligible passage] I think, was his name. One thing that I did do over there was I helped recruit Jim Meindel from Fort Belvoir out to academia. I thought he would be better off in academia than in the army. And he's done very well in the academic setting. And I got him started in medical electronics. So I think that was a fairly good thing to do.

Goldstein:

I'm interested in how involved you were with your Finnish student in the design for the MOS transistor. That's essentially different from device fabrication. How comfortable were you working with that kind of thing?

Moll:

It was work that was really very similar to the previous theoretical work on the behavior of the junction transistor. So it really was just involving the physics of electronic conduction in semiconductors.

Goldstein:

So does the design theory just consider internally what's happening in the device, or just consider the device as black box and see how it works in circuits?

Moll:

No, just internally what's happening. See, there are several levels of this question. What is happening internally to the fields, and to the conduction, and such? And there's a very simple level which is sort of a very basic kind of thing of where do you look for oxide thicknesses, and work functions, and crystal conductivity, and such. And what sort of things will happen there in a general way. That's what he did. And then as you learn how to build the things, why, you get to more and more subtle questions. So there were a lot of things that he and I didn't look [at]. But there were enough things in what we did look at that we had right.

Gallium Arsenide

Goldstein:

I know that later on - I don't know if this is in the sixties or not - you spent a lot of time looking at gallium arsenide.

Moll:

That's right.

Goldstein:

How did you get involved with that?

Moll:

Well, it was at least in part to be in the forefront of what was happening in semiconductors, which has been my center. And in this case- Well, the gallium arsenide crystals that we had were very poor. And so we were doing our own epitaxial layers, and looking at sort of materials - things like diffusion. In connection with consulting at Hewlett Packard at that time, we were looking at light emission. Most of that light emission was over here. But the gallium arsenide work at Stanford was mostly to look at the electronic properties of gallium arsenide, electronic behavior.

Goldstein:

Was Stanford a center for research in gallium arsenide? Or was that all over the place?

Moll:

Well, it was sort of all over.

Goldstein:

How did it get started? I mean I have no idea.

Moll:

Oh, there are a lot of things on the periodic table, either in combination or by themselves, which are semiconductors. Like some people are still looking at carbon or diamond. Silicon carbide, is such a combination. They also have 2-6. Almost every 2-6 crystal is a semiconductor. So there are people now who are looking at 2-6 crystals as potential optical devices. In fact, Hewlett Packard a long time ago built a 2-6 photoconductor as one of their instruments. I don't remember when gallium arsenide got started, because it seems like ever since I can remember I knew that there were just lots and lots of things that were semiconductors.

Goldstein:

So now you had this compelling theoretical reason why silicon would be useful in the semiconducting switch. I wonder if you had the same, or a similar, idea about why gallium arsenide was important for a particular device.

Moll:

No. At this point in time I would say that the 3-5 compounds have a great future as optical devices. But I wouldn't want to bet on them to displace silicon integrated circuits. In fact, none of them have the stable oxide that silicon has. If one of them would have a stable oxide and an oxide-to-crystal interface, then there could be places where it would be a competitor. I mean that doesn't make it a winner for sure. It makes it a potential candidate.

Keeping Up with Literature and HP

Goldstein:

During this period, maybe even before, what literature [did] you feel obliged to keep up with?

Moll:

Well, I've been a member of APS for a long time, but I started out with IRE, which turned into IEEE. And that's been my center really.

Goldstein:

The Transactions?

Moll:

It was the Transactions, and then it turned into the Transactions on Electron Devices, [that] would be the center of the IRE things.

Goldstein:

Is that where the important work shows up?

Moll:

The things that are most important to me would show up there or in the Letters. Or nowadays sometimes things will show up in Physics Today. But the things with most interest I guess are still IEEE publications.

Goldstein:

Is a lot of your work inspired by an awareness of what else is going on? And is it necessary for you to keep up on things? Or do you do it as a matter of interest?

Moll:

Well, the way that I work now is more as a consultant to younger people here at HP. I have a hobby, which is to use computers to solve physical problems. And a couple of years ago I got a copy of Mathematica, which I've enjoyed very much. And so that's one of my hobbies, you might say.

Goldstein:

How did you come to be involved with HP? I guess you were consulting for them even while you were at Stanford?

Moll:

Yes. Almost all of my consulting at Stanford was with HP. See, the guideline that Fred Terman had was that you could consult the equivalent of one day a week. You could do it in two half days which was most convenient. So I would be out here two [and a] half days a week. I got to know Hewlett Packard very well. And when Hewlett Packard Associates started in the early sixties, I helped Jack [Unintelligible Passage] who was the person starting Hewlett Packard Associates to recruit people. I knew people in the semiconductor engineering community, and he didn't. So I added that. So I was also on the Board of Directors of Hewlett Packard Associates. Hewlett Packard had something like a 60 percent interest to start with, something like that and in 1964 they bought out the 40 percent interest, and turned this into a division, into the Components Division of Hewlett Packard. Now that has become the Optoelectronics Division and, I think, the Microwave Components Division. They're two divisions now that that has turned into. See the Microwave Components recently purchased another little company. Oh, what's its name? If the guys in that company knew I couldn't remember, they'd kill me. I think that the Optoelectronics has a big part in Hewlett Packard's future, particularly as being part of communications. But those two components divisions are now, I think both of them, doing fairly well.

Goldstein:

Did you end your term at Stanford and then come to Hewlett Packard?

Moll:

Except for this interval of a few years at Fairchild. When I found out that Hewlett Packard was starting up a silicon laboratory, I came back. I came back to Barney Oliver, and I told him I would like to have a job there. So we had lunch, and I guess over the lunch, why, we decided that I ought to come back.

Goldstein:

When was that?

Moll: That was in 1974.

Work at Fairchild and Consulting

And there was about '70 to '74, either three or four years in there that I was at Fairchild.

Goldstein:

Doing what sorts of things?

Moll:

I was managing the research and development in the Optoelectronics Division. They almost went out of the optoelectronics business, and I ended up consulting with their Discrete Devices Division for about six months or so. And that's why I came to this rather peculiar thing that they were doing a lot of their discrete devices the way we did them at Bell.

Goldstein:

Do you remember establishing any objectives, you know, management objectives, at Fairchild? Things that you planned to implement or goals you set for the research division?

Moll:

I have never been a terribly good manager in terms of the modern terminology on managers. I do better with working with the people that are doing the technology problems and setting objectives for them. Rather than setting management objectives.

Goldstein:

Well, can you think of a legacy from your term there?

Moll:

Oh, Fairchild is gone. It disappeared.

Goldstein:

Right.

Moll:

But, no. In consulting with the engineers in the Discrete Division, I looked at what they were doing, and they were using 75 furnaces to build what they were building. And so I told them that they could do it with 25 furnaces because they just- They would get something started, say, at 1250º, and there it would stick. And they'd have a whole bunch of temperatures at a few degrees difference, and you'd have to fix the furnace. Because if you go up and down in temperature, you break the quartz tubing very quickly. It gets cracked from the expansion and contraction. So you just put it there and let it sit. And most of the time it would be doing nothing but waiting for the next time they needed it, but the tube wouldn't crack. So all they had to do was to bring similar processes all to the same temperature, and they could build their devices with a much smaller number of furnaces.

Goldstein:

That's a good plan.

Moll:

That's something that happened. It happened after I left, but there was one engineer there that believed it could be done, and he went ahead and did it.

Goldstein:

Would you say that example is characteristic of your work as a consultant? You know, they have some project going, and your experience and expertise brings some efficiency to the operation?

Moll:

Well, in a manufacturing operation, yes.

Goldstein:

But not in research?

Moll:

Well, in research, I guess one thing that I'm very proud of is what I've been able to get started here, is to sort of lay out the direction that I thought the device process simulation ought to go, and we started with very poor computers. But I told the people that were doing the programs that they should not worry about the program, the length of it or the time. They should just be sure they get the right answer, because the computers would catch up with them. Now they're doing these things on desktop computers, and the device-and-process simulation is very powerful.

Goldstein:

This is an initiative of yours?

Moll:

Yes. And this actually has spilled over a little bit onto Stanford and into some start-up company. There are some start-up companies in the region that we work with.

Goldstein:

When did you get started doing this?

Moll:

In 1974.

Goldstein:

And what kind of computer systems were you talking about then?

Moll:

We had the HP1000 with a megabyte of memory.

Goldstein:

And people would time share? This was a central computer that had terminals? It sounds like what you're saying is well-suited to workstations, and I'm just wondering how you imagined individuals working with the computer. How did you have it managed?

Moll:

Well, let's see. In our case, why, they had to schedule time.

Goldstein:

Oh, they did? I see.

Moll:

We had a little computer room [where] we took care of the computer. And of course the- Well, now we're putting in 64 megabytes of memory into computers, and they're much faster, [they] can do much more complicated problems.

Inefficiency in Development and Staying Active

Goldstein:

We may be drawing to a close. I'm just wondering if there are any highlights to your career that we may have overlooked. For instance, I was unaware of what you just told me, and you said that's something that you're very proud of. Is there anything else like that?

Moll:

Well, see, that's something that has stayed and has been very successful here. I'm always in the middle of something, of complaining because people don't do it well enough, or I'm not satisfied with it. I'll tell you what my latest very specific thing is, and that is that we should try to design our technology so that, as it moves ahead, we learn from the last experience. Now, if you don't do that, then every time you take a step, you have to invent everything. And too often we will make what looks like a small step in technology, but it turns out to be a big one because we don't take enough advantage of what happened in the last five years. And that is where inefficiency comes in to our technological development, and that is something that I try to keep talking about.

Goldstein:

Who is in a good position to be on the lookout for that? Is it managers or engineers?

Moll:

It's probably experienced engineers in that particular line of development. Because the managers very quickly lose enough track of - and can't have enough - detailed understanding of what's going on. I would not want to count on them. The people that we call project leaders and the half dozen or so engineers reporting to them at most. Which I guess that was sort of like what I was at Bell. These people are in the best situation because they have a pretty good view of what they're trying to do. To be in that position they should be experienced enough in that technology that they know what has happened in the last ten years.

Goldstein:

When I look through your papers, I see that, you know, you're still authoring or co-authoring a lot of papers, which suggests a pretty active research role. Is that accurate?

Moll:

Well, I'm not nearly as active as I was 20 years ago.

Goldstein:

How do you get involved in the authorship of these papers? What is your role?

Moll:

As a result of working with people, of advising them. And then sometimes even telling them what the answer should be and they were going in the wrong direction. See, this is something about computers that I have always preached, maybe incorrectly, but this is one thing, and that is, if you don't know what the answer should be, you should never put it on a computer. You should understand the problem well enough that you don't have to put it on a computer to know what kind of an answer you should get. Now, if you know what kind of an answer you should get, then go to the computer and get it to three decimals which we need to have in almost everything that we do now.

Goldstein:

So it sounds like you're offering methodological guidance?

Moll:

I suppose, yes.

Goldstein:

Well, I may be done with questions. Is there anything you'd like to add? Some stage of your career that you think we didn't cover in enough depth? Nothing like that?